JP's Auto Repair

07/04/2026

PSA: Stop buying bargain-bin Amazon parts to fix your vehicle.

If those parts aren't coming from a reputable supplier, the prices are often too good to be true—and they can end up costing you far more in the long run.

This 2013 Hyundai came to us with a complaint that it would stall once it reached operating temperature.

The first thing I noticed was that it had a pile of new parts installed: a new crankshaft position sensor, new VVT solenoids, and what appeared to be a new set of fuel injectors.

We connected the lab scope to the crankshaft position sensor and immediately found an erratic signal. Comparing it to a known-good waveform confirmed the sensor was faulty, despite being "new."

After replacing it with a quality sensor, the crank signal was clean—but the vehicle still stalled once it warmed up. It would run and drive down the road just fine, but after reaching operating temperature, it would repeatedly stall at idle.

Looking at the scan data, the fuel trims were heavily negative, indicating the engine was trying to remove fuel. To verify what we were seeing, we induced a vacuum leak. Under normal circumstances, that should have driven the fuel trims well into the positive range as the engine compensated for the extra air. Instead, they stayed negative the entire time. The only thing that changed was that the engine would continue idling.

That pointed us toward a fuel delivery problem.

I ordered a quality injector from a reputable supplier and put it on the flow bench alongside the injectors that were already installed. The results weren't even close. The injectors that had been installed were flowing nearly twice what the correct injector for this engine should flow.

Fortunately, I have enough experience with engine management systems to recognize what the data was telling me, so this didn't turn into an even bigger diagnostic nightmare. But it still cost unnecessary diagnostic time that could have been avoided.

Here's the takeaway:

Your mechanic can't accurately diagnose your vehicle if you install questionable aftermarket parts and assume they're good simply because they're new.

There is absolutely nothing wrong with trying to save money on parts. But buy them from reputable manufacturers and trusted suppliers. Cheap, no-name parts can create brand-new problems that look like something completely different.

In the end, those "great deals" can cost you far more in diagnostic time, additional repairs, and frustration than buying quality parts in the first place.

07/03/2026

2013 Hyundai Elantra. Stalls after it warms up. Let's diagnose it

JP's Auto Repair is located in Fairbanks, Alaska.

07/02/2026

Is your AC not blowing as cold as it used to? Remember your HVAC system has to be able to breathe to properly function. If you can't remember the last time you change your cabin air filter it is probably due. This 2023 ram AC system was not blowing optimally cold. The AC system was charged adequately, the pressures in the AC system are correct, it is just not getting as cold as it should. We found that the cabin air filter was severely restricting air flow, and not allowing enough air to move across the evaporator core. Unfortunately we didn't check the temperature output before. A properly functioning AC system should be somewhere in 40f range

06/29/2026

We had to make a hard decision, as there has just been too many no call no shows as of late and it's costing our other customers availability that they could really use to get their vehicle fixed.

We have made the decision to now require a $50 deposit for an appointment, this deposit WILL be applied to your visit. It is however a non-refundable deposit.

The exceptions to this are potential warranty repairs.

We appreciate your understanding in this matter

06/29/2026

At JP's Auto Repair, we know there are a lot of good mechanics out there. What we've always wanted to set us apart is our commitment to diagnosis—not guessing.

We have invested in a wide range of advanced diagnostic equipment that allows us to narrow down and verify what is actually causing a problem before recommending repairs. Too often, vehicles end up at shops where parts are replaced based on an educated guess. Our goal is to gather as much conclusive evidence as possible so we know we're fixing the right problem the first time.

In this video, you'll hear some screeching at the beginning as we attach our diagnostic equipment to the idler pulley. After that, you'll hear a very noticeable whining noise coming from the drive belt area.

Our testing confirmed that the noise is 100% coming from inside the generator battery control module (alternator). This is a very expensive component, and it would be unfortunate for both the customer and our shop if we replaced it based on a guess. Because of the testing we performed, we have enough conclusive evidence to confidently say the noise is originating internally from the alternator. That means we can provide an estimate knowing we're addressing the actual problem—not hoping we are.

We handle all kinds of advanced diagnostics. If your vehicle has been to multiple shops and you're still searching for answers, give us a call or send us a message. We'd be happy to help.

We're not perfect, but every day we strive to be as close to it as we can by letting the evidence—not assumptions—guide our repairs.

06/22/2026

2019 Jeep Wrangler. It has an intermittent check engine light with numerous communication codes. This is why diagnostic equipment is extremely important, the modern vehicle can have over 50 modules on board that all communicate with one another. And between manufacturer to manufacturer they all have different ways they hook into the network for each and every module. Chrysler uses what's called a star connector. The star connector has multiple modules that all tie in together on it, it is just a little circuit board with terminating resistors in it. That's main job is to bridge all of the modules together so they can all talk. This vehicle came to us from another shop, and here's what we found. This thing needs a star connector to repair it

06/18/2026

Exactly why us professionals do not use stop leak. There are little cores that fluid has to flow through to properly cool your vehicle, that stop leak not only plugs the hole that was leaking, but also plugs up those cores. Now this vehicle not only needs the coolant leak fixed, it now needs a radiator a cooling system flush, a new thermostat, and the heater core completely flushed out and hopefully it can be flushed out. This just significantly increased the cost of repair because of a $20 magic bottle of stop leak..,...

06/17/2026

Remember, we service R134A and R1234YF AC systems. If you are having issues with your AC don't hesitate to give us a call or text 907-330-9505

06/08/2026

We do bench flash/test ECUs as well. Trying to tune an 03 Silverado and can't get it to program in the vehicle, so I had to pull the ECU, there's some aftermarket accessory somewhere creating interference that is causing the programming to fail. This isn't an ideal situation for this specific instance, because this job requires multiple recalibrations of the ECU.

If you're unsure if your ECU is the problem, we can bench test it.